With the rapid development of microelectronics processing technology, users require higher quality of the product, which prompts enterprises to continuously improve the production equipment and process so as to meet new market demands. As an important microelectronic processing technology, the semiconductor integrated circuit industry is developed at a remarkable speed. Fabrication of the copper interconnect layer in the integrated circuit is a very critical technique among other processing; and at the current stage, such process is implemented using physical vapor deposition (which is called PVD for short).
Referring to FIG. 1, which shows the main processing sequence of the PVD process. As shown in the figure, several steps such as degassing, pre-cleaning and Ta (N) deposition are performed before depositing Cu. Degas refers to the process step of heating-up the substrate to certain temperature (usually 350° C. or higher) in order to remove water vapor and other volatile impurities on the substrate. As the first step of the PVD process, the degas step has an important function. During heating the substrate, it is required to heat up the substrate rapidly while ensuring uniform heating-up of each area on the substrate. Otherwise, uniformity in the subsequent steps will be affected, or even causes the problem of substrate broken. In view of above, a dedicated substrate heating apparatus has been proposed.
Referring to FIG. 2, which shows the schematic structural view of a widely used substrate heating apparatus. The apparatus comprises a heating chamber 1, a substrate support platform 2 provided inside the heating chamber 1, wherein a heating wire assembly 4 is provided in the interior of the substrate support platform 2; several heating lamps 3 are uniformly arranged in the upper portion of the heating chamber 1; a sealing quartz window 5 and a hot plate 6 are provided between the heating lamps 3 and the substrate support platform 2, the sealing quartz window 5 dividing the heating chamber 1 into vacuum and air potions, and wherein the heating lamps 3 are disposed in the air portion, while the hot plate 6 and the substrate support platform 2 are disposed in the vacuum portion.
The workflow of above apparatus is as follows: firstly, the substrate 7 to be heated is placed on the upper surface of the substrate support platform 2, then it is heated by both the heating lamps 3 and the heating wire assembly 4; the heating lamps 3 irradiate the hot plate 6 in the heat radiating manner and heat it up, the hot plate 6 subsequently heats the substrate 7 thereunder, such that the substrate 7 can be heated up rapidly and uniformly by means of the rapid heating-up characteristic of the heating lamps 3 and the heat spreading effect of the hot plate 6.
However, during the degas process of the substrate, the heat dissipation rate at the edge region of the substrate 7 is significantly higher than that on the center region of the substrate. Therefore, in order to keep a uniform heating rate for the edge region and the center region of the substrate 7, the edge region needs more heat irradiation so at to compensate the heat dissipation. To this end, the technicians adopt a solution whereby a partitioned control is provided to the heating lamps 3 for the edge region and those for the center region of the substrate 7, so as to achieve optimal heating effect on (on  of) the substrate.
Now referring to FIG. 3, which shows the arrangement of the heating lamps in the apparatus shown in FIG. 2. In the circular heating chamber, a plurality of the heating lamps 3 are arranged along the periphery of the circular chamber, and are set into an inner loop and an outer loop which correspond to the edge region and the center region of the substrate 7 respectively. By controlling the power of the heating lamps 3 in the inner and outer loops independently, a partitioned heating to each of the edge region and the center region of the substrate can be achieved. According to above partitioned heating scheme, by increasing the power of the heating lamps 3 for the edge region of the substrate 7, the heat dissipation at the edge region of the substrate 7 can be compensated to some extent. However, because of the hot plate 6 disposed between the heating lamps 3 and the substrate 7 in the substrate heating apparatus shown in FIG. 2, the heat radiation from the heating lamps 3 for both the edge region and the center region of the substrate 7 will be absorbed by the hot plate 6 firstly and cause the temperature of the hot plate 6 rise, then the substrate 7 will be heated by the lower surface of the hot plate 6 by the uniform heat radiation. That is, after the processing of the hot plate 6 to the heat generated from the heating lamps 3, the partitioned heating effect described above will be reduced, such that the heat dissipation at the edge region of the substrate 7 may not be compensated effectively, and the uniformity of the substrate heating-up will be affected.